Gondwanatheria

Mandible fragment of Sudamerica ameghinoi

• Continents of the southern hemisphere

The Gondwanatheria are a group of extinct mammals that (former Gondwana ) lived from the Upper Cretaceous to Eocene in the in the continents of the southern hemisphere.

The findings so far are limited to teeth and parts of the mandible. The molars are hochkronig and have transverse hump on. This construction is reminiscent of the the Multituberculata, one at the same time living in the northern continents mammal group, so the earlier findings of Gondwanatheria were classified into this group. However, the jaw parts found to show significant differences: the Gondwanatheria had four molars ( Multituberculata only had two ) and their premolars did not exhibit the jagged bumps that group. From the findings, it can be concluded that it is likely to have acted very small, mostly herbivorous mammals.

The most and best preserved finds of Gondwanatheria come from South America, specifically from Patagonia, where the genera Ferugliotherium and Gondwanatherium from the Upper Cretaceous and Paleocene Sudamerica are known. From Madagascar, the genus Lavanify is known so far untitled material was also found in India, Tanzania and Antarctica. The Antarctic finds come from the Seymour Island and are around 40 million years ago known recent; they suggest that the Gondwanatheria could have survived on the continent up to it from freezing. Overall, these animals are likely to have occurred on all continents of the former Gondwana.

The Gondwanatheria relationships with other mammalian groups are still controversial. Sometimes a relationship is assumed to Multituberculata and classified both groups in the plant species of Allotheria. Although the construction of the jaw rather speaks against this relationship, they could be expected but similar ecological niches - small, herbivorous mammals - have occupied that were later adopted by the rodents. Others, however, now largely discarded theories see in the Gondwanatheria relatives of the Xenarthra, or monotremes ( which occurred in the Paleocene in South America ). Still other theories consider them as isolated, with no other mammal group more closely related side branch. Without new, better finds, these questions can not be answered well, however.

Swell

• Thomas S. Kemp: The Origin & Evolution of Mammals. Oxford University Press, Oxford 2005, 331 pages, ISBN 0-19-850761-5.
• Mesozoic Mammals: Gondwanatheria